Hydraulic motor control



May 5, 1959 I C. G. GORDON @Pfau a@ 0,1/

@M www 2,884,904 HYDRAULIC MDTOR CONTROL Application November 4, 1954,Serial No. 466,925 4 Claims. (Cl. 121-39) The present invention relatestoy hydraulic motor control apparatus which is designed to be used ininllight refueling apparatus.

A broad general object of the invention resides in pro viding a novelhydraulic motor control by which the fluid ow to and from a hydraulicmotor is controlled in response to the load on the hydraulic motor.

A further object resides in providing a hydraulic motor' control inwhich iluid ow to and from the motor is directed in response tovariations in motor load reected by pressure changes in the motoroperating fluid balanced against a reference pressure source.

Further novel features and other objects of this invention will becomeapparent from the following detailed description, discussion and theappended claims taken in conjunction with the accompanying drawingshowing a preferred structure and embodiment, in which:

The single figure is an enlarged diagrammatic view illustrating ahydraulic motor control in accord with this invention, shown in thefluid line connections to a reversible hydraulic motor which is driveconnected to I an inight refueling hose and drogue reel, the load on themotor.

As the present hydraulic motor control invention was conceived inconnection with inight refueling apparatus, the schematic constructionshown in the 'drawing shows a refueling reel carrying a trailing hose 22with a drogue 18 attached to the extremity of the trailing hose todepict a load on a rotary hydraulic motor 38. The motor 38 is reversiblefluid motor, preferably a positive displacement type, and can be chosenfrom many such wellknown motors.

The precise sequential operation of the entire apparatus, andspeciiically the hydraulic motor 38, is best apparent from aconsideration of the drawing. Within a control box (not shown) which canbe mounted on reel support structure closely adjacent the motor 38y ismain control valve 87 having a rotary valve body 88 to which there isattached an external lever arm 90. The precise rotary control valvestructure 87 preferably employed with the invention is a hydraulicallybalanced fluid valve such as is shown in the co-pending Gordonapplication Serial No. 384,196 entitled Balanced Fluid Valve, now PatentNo. 2,822,821, although other valve means having similar characteristicscan in all probability he employed with the invention with varyingresults depending upon the characteristics of such` other valve means.

When the rotary valve body 88 and the lever arm 90 are in the positionsshown, hydraulic fluid from an appropriate source of hydraulic fluidunder pressure (not shown) is conveyed to this valve 87 by means ofapipe 91 so as to place a central passage 92 within the' valve body 88under pressure. As the lever arm 90 is turned in a clockwise directionas viewed in the drawing, by means of al solenoid 95 being actuated soasf to cause part of this solenoid to bear against the lever armI 90,`the-central passage 92 is placed in communication with United StatesPatent t) passages 96 within the valve 87. These passages are joinedtogether within this body in vsuch a manner that as the rotary valvebody is turned in this direction liuid flows from the pipe 91 throughthe central passage 92, and thence into these passages 96 and out into acommon pipe 97. Simultaneously, return passages 98 within the controlvalve 87 are placed in lluid communication with side passages 100 formedwithin the valve body 8S, permitting hydraulic uid to llow throughpassages 101 within the valve 87 into these side passages 100 and intothe return passages 98, and thence out of the valve ,87 through a pipe102 serving to conduct hydraulic fluid back to an appropriate reservoir.The passages 101 are connected to a common pipe 103 leading from thevalve 87.

If the lever arm 90 is rotated in a counterclockwise direction as by asolenoid 105 being `actuated so as to cause part of this solenoid tobear against the lever arm 90, the valve body 88 within the valve 87will be moved in such a manner that hydraulic fluid flowing through thepipe 91 will be conveyed throughpthe central passage 92 to the passages101 and the pipe 103, and, simultane ously, the return pipe 102 will beconnected by means of the side passa-ges 100 to the passages 96 and thepipe 97. It is seen from this description that by rotating the lever arm90 in either a clockwise or a; counterclockwise direction, essentiallythe same type of fluid ow is created within the valve 87 except for onemajor difference. lf this lever arm 90 is' rotated in one direction, thepipe 97 will convey hydraulic liuird under pressure from the pipe 91,and the pipe 103 will be in communication with the hydraulic fluidreturn pipe 102; whereas if the lever arm 90 is rotated in the oppositedirection, the pipe 91 serving to connect the valve 87 to a source ofhydraulic fluid under pressure will be connected to the pipe 103 whilethe pipe' 97 will be in communication with the hydraulic iiuid returnpipe 102.

The pipes 102 and 91 are preferably respectively connected to anappropriate hydraulic reservoir (not shown) and a hydraulic pump (notshown) of conventional cate'- gory to which the hydraulic motor 38 isattached.

The direction of rotation of the hydraulic motor 38 is dependent uponwhether the pipe 97 or the pipe 103 is used to convey fluid undervpressure from the control valve 87 to: the motor 38 and direction ofrotation of the hydraulic motor 38 may be reversed by moving the leverarm 90 of the control valve 87. One important feature of the instantinvention lies in the' fact that it is possible to Very closely regulatethe hydraulic motor 3S so as to obtain any desired rotational speed,depending upon the position of the lever arm 90.

The pipe 103 is connected to a branch pipe 120 which leads directly to asmall hydraulic cylinder 121 so that the interior of this cylinder isplaced in fluid communication with the pipe 103:,` and so that theposition of a small piston 122 within this cylinder 121 may -beregulated by the fluid pressure within the pipe 103 so as to cause aprojecting arm 125 attached to the piston 122 to bear against the leverarm 90. The pipe 120 is provided with a ibranch` pipe 126 through whichhydraulic iiuid from the pipe 103 is conveyed past a 'solenoidcontrolled valve 127 to a second hydraulic cylinder 128. This cylinderis equipped with a piston 130 which is adaptedto be moved by hydrauliclluid under pressure conveyed to it from the pipe 103. This piston isprovided with aprojee'tingl al'rn 1311 which is adapted to bear againstthe lever` arm 90 on the side of this arm' remote fi-'oni the projectingarm` 125i` Thus, with this construction, the lever armi 90 may be moved'in either a clockwise or' a counterclockwiseV direction as' either ofthe pistens 122 or 1'350is* moved within the hydraulic cylinders 121 or128; In effect, these' pistons aref balanced against one another by theprojecting arms 125 and 131 bearing against the lever arm 90. Betweenthe solenoid control valve 127 and the hydraulic cylinder 128 there isconnected to the branch pipe 126 a hydraulic accumulator 132 which isemployed for a purpose as will be more fully described.

One major advantage in the use of a positive displacement hydraulicmotor 38 with the instant invention lies in the fact that the pressureof the hydraulic lluid employed to drive this member is directly relatedto the load placed upon the motor. Thus, with the construction shown andillustrated in the drawings, the amount of drag placed upon the drogue18 and the extended hose by the airstream during the operation of theinight refueling apparatus results in a tension force through the hose22 to the reel 25, which varies with varying airspeeds and can bedetected by means of the hydraulic pressure employed to turn thehydraulic motor 38. With the construction illustrated in the drawings,the pressure of the hydraulic uid used in the hydraulic motor 38 may beemployed so as to automatically regulate the operation of the hydraulicmotor by turning the control valve 87 so as to keep any desired amountof tension within the hose 22.

With the construction shown the branch pipe 120 is employed to conveyhydraulic uid under pressure to the hydraulic cylinder 121, thehydraulic cylinder 128, and the various attached pipes and members asindicated in the preceding discussion. These hydraulic cylinders andattached members and parts are all located within a control box alongwith the control valve 37. When, by virtue of operation of theappropriate solenoid 95 or 10S, ythe motor 38 has been operated so thatthe hose 22 is extended by rotation of the reel so as to place thedrogue 18 in a position in which it may be employed in inflightrefueling, the lever arm 90 is returned under solenoid control to theposition shown in the drawing. At this point the valve 127 is in openposition so that the hydraulic `cylinders 121 and 128 are balancedagainst one another; that is to say, the projecting arms 125 and 131attached to the pistons 122 and 130 within these hydraulic cylinders areboth extended against the lever arm 90 in such a manner that this leverarm is centered. At this point, when, as above noted, the drogue andhose are in extended operative position, the solenoid control valve 127is closed, keeping the hydraulic fluid within the hydraulic cylinder128, the branch pipe 126, and the hydraulic accumulator 132 at asubstantially fixed pressure. As the pressure within the pipes 120 and103 varies thereafter, this variation will be transmitted to thehydraulic cylinder 121 causing the piston 122 to either be retractedwithin this cylinder or extended therefrom an amount proportional to thedifference in pressure between the pressure in the cylinder 121 and thepressure in the cyliuder 128, simultaneously causing appropriateclockwise or rcounterclockwise rotation of the lever arm 90. Suchrotation of the lever arm 90, as previously described, governs therotation of the hydraulic motor 38, and thus, will cause the hose 22 tobe either reeled in or reeled out at a speed proportional to the amountthe lever arm 90 is rotated.

This mechanism is exceedingly important for inflight refueling inaccordance with the instant invention inasmuch as with it the load uponthe hose 22 may be regulated so as to obtain very satisfactory inflightrefueling characteristics. Thus, with the construction shown, as thedrogue 18 is engaged by a following aircraft to receive fuel, thepressure within the pipe 103 will automatically drop as the drogue 18 ispushed towards the apparatus 10 by virtue of the motion of the receivingaircraft engaging the drogue coupling which reduces drag on hose 22,decreasing hose tension and reducing the load on the hydraulic reelmotor, which is working against the hose drag. This change in pressurein the pipe 103 will be reected by the means indicated above 4l l so asto rotate the lever arm 90, causing the hose 22 to be reeled in upon thereel 25. As an aircraft being ret fueled in flight drops behind thecomplete inight refuel- I ing apparatus, the increased pull upon thehose 22 will 'be reected by an increase in the pressure of fluid withinthe pipe 103, and will cause, by means described above, the lever arm tobe rotated in such a manner as to operate the reel 25 to extend thehose. Thus, with the instant invention, an exceedingly simple, veryelective apparatus is employed to keep the precise amount of tensiondesired upon the hose in inight refueling, regardless of minorvariations of speed within the receiving aircraft and the aircraftemployed to convey fuel to this receiving aircraft.

A pipe 135 is shown connected to the pipe 91 so as lo convey hydraulicfluid from this pipe 91 under pressure past a dheck valve 136 and ahydraulic accumulator 137 to a solenoid controlled valve 138 which isused to gorern the admission of hydraulic fluid into the brake cylinders37. For convenience of explanation, only one of these lcylinders isindicated in Fig. 5 of the drawings. Spent hydraulic fluid is conveyedby means of a pipe 139 back to the pipe 102 which carries it to anappropriate reservoir for hydraulic iluid. The valve 136, theaccumulator 137, and the valve 13S are all, for convenience, locatedwithin the control box.

It will be realized by those skilled in the art that a number of minormodifications may be made within the basic teachings of thisspecification without departing from the essential features of theinstant invention. For this reason, the present invention is consideredto be limited by the appended claims forming a part of thisspecification.

I claim as my invention:

l. Control means for use in governing the operation of a hydraulicmotor, comprising: a valve, including a movable element, adapted to beconnected to a hydraulic motor so as to control iiow of hydraulic fluidto and from the motor and control rotational operation of the motor; anarm attached to said movable element shiftable in a path between twopositions to thereby operate said valve to control flow of hydraulicfluid; servo-motor means for moving said arm toward either position froma neutral position; a reference pressure source connected to bias saidservo motor means in one direction; conduit means adapted to beconnected in fluid communication with the operating uid between saidvalve and the hydraulic motor and in fluid communication with said servomotor means so said operating iiuid will oppose the bias of saidreference pressure source whereby variations in motor operating pressurewill result in servo motor actuation of said valve to maintain operatingpressures to a predetermined value as represented by said referencepressure source.

2. A control means as defined in claim 2 including means connectedbetween said reference pressure source and said conduit means fordisabling said servo motor means and means operably connected to saidarm for moving said arm independently of said servo motor means.

3. Control means for use in governing the operation of a hydraulicmotor, comprising: a valve including uid pressure inlet and outlet portsadapted to be connected to a source of and return to pressure fluid, twoports adapted to be connected to the operating lines of -a hydraulicmotor, a movable valve element adapted to be positioned to alternativelyconnect either one of said two ports to a pressure source and the otherof said two ports to return or to block all flow between pressure andreturn ports and said two ports; an actuating arm connected to controlsaid movable valve element; a double acting servo motor meansoperatively connected to said operating arm for valve controllingmovement; a first uid conduit in communication between one of said twoports and one side of said servo motor means; an

accumulator in fluid communication with the other side of said servomotor means; a second fluid conduit in communication between saidhydraulic accumulator and said one side of said servo motor meansincluding a shut-off valve.

4. A device, to be utilized in governing the operation of a hydraulicmotor, which comprises: a valve connected to said hydraulic motor so asto control the ow of motor operating hydraulic uid to and from saidmotor; a movable element included in said valve; a control arm attachedto said movable element so that as said control arm and movable elementare shifted, the flow of hydraulic fluid to and from said hydraulicmotor is controlled; a reference pressure source; and means responsiveto dilerences in pressures between said reference pressure and thepressure of hydraulic fluid within said hydraulic motor for shiftingsaid control arm an amount proportional to said differences in pressurewhereby the pressure of hydraulic uid within said motor is maintained ata value represented by said reference pressure source.

References Cited in the le of this patent UNITED STATES PATENTS1,718,673 Wettstein June 25, 1929 1,815,100 Francis July 21, 19312,071,594 Trumbach Feb. 23, 1937 2,490,353 Hannay Dec. 6, 1949 2,536,965Taylor Ian. 2, 1951 2,573,868 Newell Nov. 6, 1951 2,573,938 Tyler et al.Nov. 6, 1951 2,596,455 Williams May 13, 1952 2,615,756 Granberg Oct. 28,1952 2,669,226 Adams Feb. 16, 1954 2,674,853 Born Apr. 13, 19542,692,102 Cobham et al. Oct. 19, 1954 2,723,833 Burfeind Nov. 15, 19552,764,365 Davis et al Sept. 25, 1956 2,789,542 Vander Kaay Apr. 23, 1957FOREIGN PATENTS 136,889 Sweden Aug. 12, 1952 314,523 Germany Sept. 25,1919 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No.2,884,904 May 5, 1959 Carroll G. Gordon It is hereby certified lthaterror appears in the printed specification of theA above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

KAEL H.. AXLTNE Column 4,. line' 55,- for the claim reference numeral"2" read l Signed and sealed this 25th day Lof August 1959.

(SEAL) Attest:

ROBERT C. WATsoN Attesting Ocer Commissioner of Patents

